A traditional hoist consists of a motor connected to a spool, which is used to wind a cable up and down to move a payload vertically. Typically, these devices are remotely controlled with various up/down buttons on a pendant. By attaching the payload to the end of the hoist cable, a human operator can raise and lower heavy payloads by simply pressing the pendant's buttons. This type of hoist can be found in many manufacturing operations requiring movement of payloads that are too heavy for human operators. Though traditional hoists are indispensable for their tremendous load lifting capabilities, their slow, non-variable speeds, and remote controlled operation can be less than ideal for many manufacturing applications.
Consider a simple automotive assembly procedure such as placing an engine block on its engine mounts. During the assembly sequence, the operator raises an engine block from the factory floor, up and over the front fender, into the engine bay and onto the motor mounts. An extremely wide range of speeds would be desirable for this task. While moving from the factory floor to up and over the front fender, it would be desirable to move at quick human-like speeds. Slower speeds would be desired while lowering the engine block into the car's engine bay. Finally, extremely low speeds with regular changes in direction would be most suitable when precisely placing the engine block on the engine mounts. This would be inefficient and frustrating, even with a highly skilled operator using a dual speed hoist. The high speed command would not be fast enough for moving from the factory floor to up and over the fender and the slow speed would not be slow enough for precise placement on the engine blocks.
Poor performance is tolerated in applications requiring super-human strength because there are few alternatives. However, there are countless applications in which a traditional hoist could be used to significantly reduce operator strain (for example placing a 50 pound car seat or 20 pound car battery) but is not used because of the frustration and inefficiency associated with the clumsy and slow operational features of traditional hoists.